In wireless networks using technologies, such as an Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, Worldwide Interoperability for Microwave Access (WiMAX), and/or a Third Generation Partnership Project (3GPP) standard or the like, the scheduling is centralized (referred to as dynamic scheduling) and may be performed by the base station (BS). The scheduling information is conveyed by the base station to one or more mobile stations (MS) in the form of control information that is referred to as MAP. The size of the MAP is proportional to the number of mobile stations scheduled in a given frame. If the packets to be scheduled are relatively small in size, such as in Voice over Internet Protocol (VoIP) type applications, then a relatively larger number of users can be scheduled in a frame, resulting in larger MAP overhead. Persistent scheduling is believed to be a potential mechanism to reduce such overhead. In persistent scheduling, instead of refreshing resource allocation for a given mobile station in every frame, a mobile station may be scheduled persistently for a multiple number of frames, for example, N frames. The scheduling or MAP information may be conveyed only in the first frame and then skipped in subsequent N−1 frames, thereby saving overhead.
A major problem with persistent scheduling may occur when one or more mobile stations lose the MAP information, for example due to poor channel conditions. In the case of dynamic scheduling, loss of MAP information in a given frame may result in wasted resources only in that particular frame. In the case of persistent scheduling, however, resources may be wasted in multiple frames. If a mobile station misses a MAP carrying the persistent allocation information, the base station will keep allocating resources every frame, but the allocated resources will not be used by the mobile station, thereby resulting in a waste of resources. If mobile station misses a MAP carrying cancellation of persistent allocation information, then the mobile station may continue transmitting in those resource blocks, and such transmission might collide with transmissions from one or more other mobile stations, which may result in wasted resources and/or unnecessary delay. The situation may worsen in which grouping and bitmap assignment are utilized since such information may affect multiple users, and any errors in the bitmap errors could propagate in time for several frames.
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